Heat transfer fluid



Dec. 13, 1938. J. G. FORD 2,l39,945

HEAT TRANSFER FLUID Filed March 15, 1935 WITNESSES: INVENTOR i Patented Dec. 13, 1938 UNITED -TATE 2,39,945' f p H T S E James G;"Fqr`d, Forestflills; Pa'., assigno f i WestinghouseElectric `& Manufacturing Com-' 'pam', East Pittsburgh Pennsylvania insulating purposes, as in transformersand the like."-' f This case'is a continuation-in-partof my pl plication Serial No. 656, 852, filed February 15,'

1933, and assigned tothe Westinghouse Electric & Manufacturing Company,

In network transformers, for example, suh as m are installed in congested itvomce buildings,

hazards of-public safety and of' Operating efr ficiency requ're thgdielectric, fluid to p explosion-proofl consequently, it is desirable to'eliminate oil and to substitute dielectrics that. are

non-flamrabl, but yet avoid introducingother v V i,

` s'o that simple dehydrating means may be ujsed deleterious qualities. v I It is among the objects of invent'on to 'provide generally useful heat transfer fluid, and more particularly suitable insulating and cooling fects of former insulating or 'cooling liquids, and to obtaina.. eombination of suitablequalities. as subsequently to be described more ful1y. Particular objects compr'se providing' liquid of this sort that `is non-flammable, that .is relatively 25 stable under electrical Stress, and that will remein in liquid state over rather wide ranges of temperature. Other objects will. appear Iromthe followingdescription and accompanying drawing of 'prefe'rred embodiments of this invention.

I have discovered ,that certain combinationsxof halogenated' compounds overcomemany of= the defects of such compounds and provide-liquids that are feasible for use even in network transi formers and the like. 85

that combnations-involving certain halogenated compoundsl of the naphthalene series, certain halogenated compounds of the benzene'series, and

certain. diphenyl compounds, in binary or even i e cooling liquid, nor combined withn appreciable morecomplex combination with: each other, exhibit qualities heretoforelacking in transformer Reference ismadeto the accompanying illustrative drawingshowing conventionally a, trans- 'for'mer comprising a. tank ,transformer elements designated as 2, and conductors 3. Protected within the tank is liquid for cooling and I y j electric 'is' illustrated by halogenatednaphthalene mixtures uch as chlorinatednaphthalenes.

insulating the transformer elements and leads. y For further illustration of 'the prlnciples and present preferred practiceof this invention, reference' ismade to specific embodiments thereof.

suitable halogenated naphthalenes A are dissolved in an appropriate base.

Trichlorbenzene has been'suggested heretofore as a. dielectric but for such` uses it has proved to be' uns'atisfactory in" variousrespects thathave been diflicult to` overcome. 'This inventlon minimizes the undesirable properties of'trichlorbenzene and utilizjes certain of its valuable characjtojbe' utilized 'in' the transformerjliquid.

fluid for. electrial apparatus; to overcome de- This jinventlon is predicatedon my discove'y y y I i proposed as dielectrics, but not 'the moreviscous ,`,.Pa.;,";a. 'corporatlon of u teristics to rovide exceptionally dlelectric liquid The trichlortenzene' known esthe .1; 2.4 isomr isselected prefe ably. since it 'is a'comnircially 'available -halo' enated hydrocarbon that; jexhibits 5 cons iderable "solvent amnity for 'certain' halog enated compounds, partiulafrly for ,members of,

' "the naphthalene series of h'y rocarb'ons wliicl at" Thesymmetrioal (1, 3,`"'5)"i'some'r howeverism well adapted tof" the purposes ofthisinvention. i 'Other desirable qualitiesflconducivtothevalue o 'the 'solvent dieletric :nj the' inixtu'e are rela; tively high `hen'ioa stabilit u der eleotric Stress; 'relatively low emulsiflbtionfwith Walter,

in the apparatu's; reltively* wide 'range of liquid stategin the mort re," relatively LI wsOlvent or V i dispersing power for. the oellulo'sio or resin'usinsulatin g varnishes .u ed On th 'eleotricalconduc- "torsj stabilit'y against' decornpositionby oxygen,

against the'cataIytIc eifect of moisture of; short 'wave or light radijation 'or of incident'al contani l nati'ng 'mtal`s; relatively high 'resistanm l'ow power loss and low ioniz ing power; Itisnot *intended to "limit this' nventlonj to pure"1. 2 .4.;

` trichlorbenzene' though' as theprdoninntbse 'higher or'solid" members th erebfjas'` isilating "and cooling` fluid for transforners, :nor in' `reIatively high'concentrationj'with solvent' tofform 'proporton of Organic compounds, suchasgtri chlo'rbenzene', which of themselves would DOS ess' 'man'y unsatisfactory characteristics forfdielectrio purposes, n'or 'in solution with somewhat viscous halogenated -hydfocerbon for 4 producing i lowvisoosity,liquid;

The naphthalene element ofthis corposiite dioften known 'as 'haldwaxesfiThogh individual such as halowaxes V ofl'er various"? advantages.

" Though 'certain of these mixtures are liquid and V orinated naphthalenea rather high temperatures. Thp'articular spe- 'c'ies mentioned possess ,of themselves'amelting point range of about `190-280 and boiling point range of about 550-700 F. These combinations of halowax and solvent further are 'rela-` tively stable against electrical stress and against moisture, and also are of improved resistance to burning. v

Though reference has been made to chlorinated naphthalene, this invention contemplate that 'other'hal'ogen derivative maybe substituted therefor in whole or in part, particularly flu- `li'urther ad'antages of this'invertion arejobtaina'ble 'by modification of `the solutions debe sbluble in thesecmbinations., ,Even relatively small quantities impart increased solubility tolthe naphthalenes, and'fpei'mit consider'able' decrease temperatures though high 'Chemical s tabilityiand *good electrical properties are retained Quantities up to the order" often ,or fifteen, percentmay be added for these purposes. Similarly-diphenyl l itself, or halogenateddiphenyl, such as Chlorinated or, fiuorinateddiphenyl. 'orchlorinated or flurinated diphenylioxide in small amount serve to improve the slubility of the naphthalenes and inreasethe availability of their desi'rable properties. Inbertain instances` largerl proportions of these* "halogenated compounds, for example, of

the order of 50%, by weightof the final mixture,

may also be utilized with success in practicing my invention. I In general 'the quantity of naphthalene dissolved may beincreased with increase of the dlphenyl Component. e V I In providingdielectricsfor network transformers', it is desirable to produce material .which on electrical-,decompositions generates non-inflamv mable gases. This may be accomplished byfollowing the teachingsto be disclosedhereinafter.

` The 'advantagesof the present {improved diy eletric 'liquid maybe enhanced further in' ac- 'to dissolve fluorinated hydro'carbons of straight 'chain and of cyclic nature.

' turn many possess 'the quality of eliminating not only fire point (sustained burning) buteven of eliminating flash point from ,thefcomposite delectric. As`an example'of'fluorinat'ed straight chain hydrocarbon that is ,at prsentpreferred because of its solubility, Chemical and ele'ctrical r reslstance, and ability in very small quantities to eliminate fire`h'azard, reference is made to tetrachlorodifluoroethaneC2CI4F2., For example as little as one percent of this solute raises the flash 'point to 440 F. and minimizes the fire point until ant excess for elimination burning occurs only on superheating at the boilng point The addition of three .percent of this preferred fiuorinated compound ,entirely eliminates both flash and fire points] Therefore ,three to five percentof this compound provides abundof explosionor fire hazard' from the dielectric', i i Z To provide' further 'against development of inferlor dielectric qualiti'es in this composite dielectrie under adverseconditionsof use, it may be desirable not 'only to remove' moisture during use, as heretofore mentioned in this description,

Of such solutes in* nous decompos'ition products or o! acid, or to remove any such products as may be formed.

With avoidance of moisture accumulation, this composite dielectric is capable of extended contact with cellulosic insulations and the like without appreciable impairment of their structure or insulating qualities. For the purpose of avoiding development of such destructive influences in onepreferred embodiment of this invention is presented by' V v scribed. For example diphenyl etherl is found to i c Formula I V z i e Pounds Halowax, halogenated naphthalene about 'Halowax, halogenated naphthalene, about I 58 ol 159 Halowax, halogenated 'naphthalene, about mer) s i'7'T' Tetrachlorodifluoroethane 25 These proportions may be' varied, as' for emmple, on a basis exclusive of the added flu'orinated compound, from about' twenty-five'to sixty percent 'of the halowax'c'omponents,` about seventy tetrachlorodifiuoroethane may vary from about twelve pounds to about sixty-five pounds, or from a about one to five percentof th otherelements of the solution. 'Tetrachlorethylne or pentachlorethane to 'repressflash point may be desir-" able to .the order 'of about fifteen percent.

..The 'characteristics of this preferred embodiment of the invention comprise-a specific gravity of 1.484 or about 1.5, and coefiicient of expansion resistance to deterioration by oxidation'orby hydrolyss, solidification temperature at least -20 F., specific heat 0.40 calories/cubic centimet'er,

lute viscosity s centipoises; power factor of well prepared solution 2 to 3 percent. Thus it is evident that in addition to substantiallynofifire hazard `this solutionis operative' over awide range liquid, because it possesses high s p ecific heat and because its low viscosity and its 'rapid 'change of Volume with temperature readily promote'convection Currents.

.of temperatures,` and' is well'adapted as cooling Further preferred' embodiments of this invention utilize chlrinated diphenyl; compounds 'in major proportions. f The `'following'specific example illustrates one such further embodiment.

, Formula i L Pounds Chlorlnated naphthalene (about 50% to mer)- 3395 Chlorinated diphenyl oxide or fchlor ina ted dphenyl (about 50% to 68% Cl) 643.0

Dphenyl oxide 45 71 a aaabao As in' the mixture of Formula I, thetrichorbenzene serves as a solvent for the' other ingredients. The quantity "of this trichlorbenzene,

which when'undiluted has a relatively high power chlornated diphenyl cooperates in dissolving' the chlorinated naphthalene, thereby keeping down the' content of trichlorbenzene. It is stable,tends to improve the power factor of the final liquid, and by 'reducing the vapor pressure of the mixture prevents rapid losses 'by evaporation In addition lt furnishes additional available chlorine and 'retards crystallization of the chlorinated v naphthalene.

The diphenyl oxide serves; as in the mixture of Formula I,- primarilyto lower the freezing point. In addition, it acts as a solvent for the chlorinated naphthalene and thereby aids in keeping down the total amount oftrichlorbenzene.

This dielectric mixture is completely fireproof. The gases given ofiduring decomposition 'are not combustible. In these gases hydrochloric' acid fumes are present in a predominating proportion and by their diluting eifect minimize explosion danger due to any presence of free hydrogen.

The characteristics of this second embodiment of the invention comprise aspecific gravity of 1.544 and c'oeficient of expansion of 0.00078 per C. It has no flash or fire points and possesses high resistance to .deterioration by oxidation or by hydrolysis. It has specific heat of 0.40 calories/cubic centimeter, a solidiflcation temperature below -20 F.: a viscosity of 58 seconds Saybolt at F., and a power factor of about one percent at 75 F. It possesses the same general advantages as does the first-named embodiment.

The above-stated proportions of Formula II may, to obtain other given desired physical and Trichlorbenzene 4042 Chlorinated diphenyl oxide or chlorinated diphenyl 5l0.0

Diphenyl oxide 53.6

This mixture is basically similar to that of Formula II. 'The chiorinated naphthalene ingredients are comparable to those of Formula I in that they comprise a mixture of chlorinated naphthalenes of difiering chlorine contents. The

mixture has a specific gravity of la and asolidification 'temperature muchfibelow -20 f It'has no flash or fire points and possesses high resistance to deterior'atiomf It has a specific heat and a coefllcient of expansion substantially theisa'me 5 as the solutions of Formulae I and I I; a viscosity of 52 'seconds Sayboltat 100 F., and a power factor also 'of about one percent. I e

The proportions of Formula' III'may be varied to obtain othergiven desired physical and elec- 10 trical'characteristics throughout the same general rangespr'evously 'statedfor Formula II.

For the purpose of'furtherenhancing the fire- 'resistance characteristics' of the' tmixtures of Formulae II and III, small quanttes of a fluori- 15 nated straight chain hydrocarbon may be added thereto. Thus when, the before-mentioned tetra chlorodifiuoroethane isintroduced in 'quantities up to 5% both flash and firepoints are mali cases entirely eliminated from these chlorinated diphenyl oxide and chlorinated .diphenyl mixtures. When, however, the proportions areas stated 'by the two formulae lastnai'ned, such additions are not'ordinarily 'found necessary.. I w

The fir'eproof compou'nds of this invention have particular use in meeting high standards for dielectric such as are imposedonhetWork trans:

formers, but" other uses nowwill' be evidentto those skilled in the art. For example, this dielec- 'tric is 'well suited for, insulation of Vcables, such as those comm'only filled with oil. A cable of this type is represented conventionallyjby numeral 5; in'the drawing, comprisingthisimproved dieles tric fluid 4. Liquid embodying the principles of this invention is particularly well suited as heat transfer medium not only in Strictly electrical apparatus but as cooling fluid for turbine bearings and the like, where severe requirements are imposed, particularly as to non-flammability or susceptibility to explosion.

According to the provisions of the patent statutes, I have explained the principle and mode of operation of my invntion and have illustrated and described what I now consider to represent its best embodiments. However, I desire to have it understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim as my invention:

1. As a new composition of matter a fireproot liquid at ordinary temperatures comprising at least fifteen percent of solid halogenated naphthalene compound in admixture with a liquid halogenated cyclic compound.

2. A dielectric liquid at ordinary temperatures comprising an isometric mixture of trichlorbenzene, 1.2.4. trichlorbenzene predominating, and solid halogenated naphthalene compound in solution, said compound containing from flfty to ses-'enty percent chlorine'.

3. A liquid of dielectric nature at ordinary temperatures comprising in solution twenty-flve to sixty percent solid halogenated naphthalene compound and trichlorbenzene.

4. A liquid of dielectric nature at ordinary temperatures comprising at least thirty percent of a mixture of chlorinated naphthalenes of aggregating from fifty to sixty-flve percent chlorine in solution with trichlorbenzene.

5. A liquid of dielectric nature comprising in 70 solution halogenated naphthalene, trichiorbenzene and diphenyl compound, and .fluorinated straight chain hydrocarbon for minimizing flash point.

6. A liquid of dielectric nature comprising in 7 solution substantially thirty-five to forty percent chlorinated naphthalenes aggregating from fifty to sixty-five percent chlorine, from five to fifteen percent diphenyl compound, and the balance substantially tricllorbenzene, and in additiontfluorinated straight chain hydrocarbon' up? to about flfteen percent to minimiz fianmability of the dielectric.

7.'Liquid of dielectric nature comprisng tri chlorbenzene, halognated naphthalene and fluorinated straight chain hydrocarbonfor minimizing flash point.

8. Liquid of dielectric nature comprising tri- J chlorbenzene, h'alogenated naphtl'alne and tetrachlorodifiuoroethane for minimizingfiash point. v 9. A heat transfer system comprising liquid of trichlorbenzen and halogenated' naphthalne base and up to the order of fteen percent additional liquid to r'prss flash point selected from a group consisting of fiuorinated straight chain hydrocarbon, pentachlorethane and ttrachlorethylene.

10. `A firepro'of liqud of dielectricvnature comprsing in solution solid hlogenated naphthalene, trichlorbenzene and diphenyl. i

11. A reproof 'dielectric liquid at ordinary temperatures comprising in solution solid chlorinated naphthalene, trichlorbenzene, and chlorinated diphenyl oxide.

12. A fireproof dielectric liquid at ordinary temperaturs comprising in solution solid chlorinated naphthalene, trichlorbenzene and chlorinateddiphenyl.

13. A fireproof tdielectric liquid at ordinary temperatures comprising in solution 'solid chlorinated naphthalene, trichlorbenzene and diphenyl oxide.

l form of diphnyl oxide. t v

19. A liquidi composition adapted for electrical ohlorinated naphthalene and solvent therefor in the form of trichlorbenzene and chlorinated diphenyl oxide. u i

18. As' a new composition of matter, a fireproof liquid at ordinary temperatures comprising chlorinated naphthalene, halogenated solvent therefor, and& freezing point depresser in the insulating and cooling purposes comprising sub- ,stantial amounts' respectively of solid chlorinated 'naphthalene and liqud chlorinated benzene, said' composition having a materially lower pour point than either-of said ingredients.

20. A liquid composition consisting substantially of chlorinated naphthalene, a halogenated phenyloid compound containing a plurality of phenyl groups and chlorinated benzene.

21; A liquid material suitable foruse in elec-' trical devices comprising essentially chlorinated naphthalen'e, a chlorinated diphenyl compound and trichlorbenzene.

JAMES G. 

